Amplifier circuit

This is a continuation of International Application No. PCT/JP2021/045820 filed on Dec. 13, 2021 which claims priority from Japanese Patent Application No. 2020-216193 filed on Dec. 25, 2020. The contents of these applications are incorporated herein by reference in their entireties.

The present disclosure relates to an amplifier circuit.

Patent Document 1 discloses a receiver module including a low noise amplifier, a power distributor that distributes a radio-frequency signal amplified by the low noise amplifier, and a high-performance receiver. In the receiver module disclosed in Patent Document 1, a switch is provided on a path with which the low noise amplifier is directly connected to the high-performance receiver. The low noise amplifier is directly connected to the high-performance receiver when the switch is closed while the low noise amplifier is connected to the high-performance receiver via the power distributor when the switch is opened.

Patent Document 1: Japanese Unexamined Patent Application Publication No. 2012-170121

In distribution of a signal using the power distributor, attenuation of the signal occurs. Accordingly, in the receiver module in related art, the gain of the low noise amplifier when the power distributor is used may be varied from that of the low noise amplifier when the power distributor is not used.

In order to resolve the above problem, the present disclosure provides an amplifier circuit capable of suppressing variation in gain.

An amplifier circuit according to an aspect of the present disclosure includes a first amplifier including a common drain or a common collector having variable transconductance; a power distributor connected to an output side of the first amplifier; and a first switch arranged in series on a second path, which branches from a first path with which the first amplifier is connected to the power distributor, bypasses the power distributor, and is joined to an output of the power distributor. Input impedance of the power distributor has a value different from that of output impedance of the power distributor.

An amplifier circuit according to another aspect of the present disclosure includes a first amplifier including a common drain or a common collector; a power distributor connected to an output side of the first amplifier; and a first switch arranged in series on a second path, which branches from a first path with which the first amplifier is connected to the power distributor, bypasses the power distributor, and is joined to an output of the power distributor. Input impedance of the power distributor has a value different from that of output impedance of the power distributor. The first amplifier includes multiple transistors. The multiple transistors are multiple field effect transistors in which gates of the transistors are connected to each other, drains thereof are connected to each other, and sources thereof are connected to each other or are multiple bipolar transistors in which bases of the transistors are connected to each other, collectors thereof are connected to each other, and emitters thereof are connected to each other. A transistor used for amplification is selected from the multiple transistors.

According to the amplifier circuit according to present disclosure, it is possible to suppress variation in gain.

Amplifier circuits according to embodiments of the present disclosure will herein be described in detail with reference to the drawings. All the embodiments described below indicate specific examples of the present disclosure. Accordingly, numerical values, shapes, materials, components, the arrangement of the components, the connection mode of the components, steps, the order of the steps, and so on, which are indicated in the embodiments described below, are only examples and are not intended to limit the present disclosure. Among components in the embodiments described below, components that are not described in the independent claims are described as arbitrary components.

The respective drawings are schematic diagrams and are not necessarily strictly illustrated. Accordingly, for example, the scales and so on in the respective drawings do not necessarily coincide with each other. The same reference numerals and letters are used in the respective drawings to identify substantially the same components and a duplicated description of such components is omitted or simplified.

In this description, terms, such as coincident or equal, indicating the relationship between elements; terms indicating the shapes of the elements; and numerical ranges do not represent only strict meanings but mean inclusion of substantially the same ranges, for example, differences on the order of few percent.

In this description, terms of “upper” and “lower” do not indicate the upper direction (the upper vertical direction) and the lower direction (the lower vertical direction), respectively, in absolute space recognition but are used as terms defined by the relative positional relationship based on the lamination order in a laminated structure. The terms of the “upper” and the “lower” are applied not only to a case in which two components are spaced and another component exists between the two components but also to a case in which two components are in close contact with each other and touch each other.

In this description and the drawings, the x axis, the y axis, and the z axis indicate the three axes in the three-dimensional Cartesian coordinate system. In addition, in this description, a “plan view” means viewing something from a direction orthogonal to main surfaces of a substrate.

In this description, “connected” includes not only direct connection with a connection terminal and/or a wiring conductor but also electrical connection via another circuit element. “Connected between A and B” means connection to both A and B between A and B.

In this description, ordinal numbers, such as “first” and “second”, do not mean the number of components or the order of the components but are used to avoid confusion between components of the same type and discriminate the components unless otherwise specified.

1. Configuration of Amplifier Circuit

The configuration of an amplifier circuit according to an embodiment will now be described with reference to.

is a circuit diagram of an amplifier circuitaccording to the present embodiment. The amplifier circuitillustrated inis provided in, for example, a reception circuit that processes a radio-frequency reception signal (hereinafter simply referred to as a radio-frequency signal) received with an antenna. The radio-frequency signal is a signal conforming to communication standards, such as Wi-Fi (registered trademark), Long Term Evolution (LTE), or 5-th Generation (5G). Although the radio-frequency signal is, for example, a signal of a 1-GHz band, a 2.4-GHz band, or a 5-GHz band, the radio-frequency signal is not limited to the signals in these bands.

As illustrated in, the amplifier circuitincludes an input terminal, two output terminalsand, an amplifier, a power distributor, multiple switchesto, a capacitor, and a bias control circuit. In addition, the amplifier circuitincludes paths,, andand two bypass pathsand.

The input terminalis an input terminal of the amplifier circuit. A radio-frequency signal is input into the input terminal.

The output terminalsandare output terminals of the amplifier circuit. The radio-frequency signal that is input into the input terminaland that is amplified by the amplifieris output from at least one of the output terminalsand. The output terminalsandare connected to different signal processing circuits.

The amplifieris an example of a first amplifier including a common drain (a source follower) having variable transconductance. The amplifieris a low noise amplifier that amplifies the radio-frequency signal input into the input terminaland outputs the amplified radio-frequency signal. The radio-frequency signal amplified by the amplifieris output from at least one of the output terminalsandvia the power distributoror the bypass pathor.

In the present embodiment, the amplifieris capable of varying output impedance Z depending on an operation mode of the amplifier circuit(specifically, whether the power distributoris used). Specifically, the amplifierhas variable transconductance. Accordingly, the output impedance Z of the amplifieris also variable to increase power gain of the amplifier. A specific circuit configuration of the amplifierwill be described below.

The power distributoris connected to the output side of the amplifier. The power distributorincludes two linesandfor signal output. The power distributordistributes the radio-frequency signal amplified by the amplifierto two signals and outputs the distributed signals from the respective linesand. The two signals distributed by the power distributorare respectively output from the output terminalsand. Since the input radio-frequency signal is distributed to the two signals to be output in the power distributor, the signal power of each of the two output signals is decreased to half (about 3 dB) of the signal power of the input signal.

Input impedance Zin of the power distributoris different from output impedance Zoutor Zoutof the power distributor. The input impedance Zin is the value of impedance when the power distributoris viewed from a branch point. The output impedance Zoutis the value of impedance when the power distributoris viewed from a junction point. The output impedance Zoutis the value of impedance when the power distributoris viewed from a junction point.

In the present embodiment, the input impedance Zin is lower than both of the output impedances Zoutand Zout. The input impedance Zin is, for example, less than or equal to half of the output impedance Zout. The output impedance Zoutis equal to the output impedance Zout, which is, for example, 50Ω. In contrast, the input impedance Zin has a value of 10Ω or higher and 25Ω or less and, for example, has a value of 25Ω. The specific value of the input impedance Zin is not limited as long as the input impedance Zin is lower than the output impedances. A specific configuration of the power distributorwill be described below.

The pathis an example of a first path, with which the amplifieris connected to the power distributor. The pathis branched into the pathand the pathby the power distributor. The pathis a path with which the lineof the power distributoris connected to the output terminal. The pathis a path with which the lineof the power distributoris connected to the output terminal.

The bypass pathis an example of a second path. The bypass pathbranches from the path, bypasses the power distributor, and is joined to the pathat the output side of the power distributor. The bypass pathis an example of the second path. The bypass pathbranches from the path, bypasses the power distributor, and is joined to the pathat the output side of the power distributor.

The branch pointis a node between the pathand the bypass pathsand. The branch pointis a starting point of each of the bypass pathsand. Although the starting points of the bypass pathsandcoincides with each other in, the starting point of the bypass pathmay be different from the starting point of the bypass path.

The junction pointis a node between the bypass pathand the path. The junction pointis an end point of the bypass path. The junction pointmay coincide with the output terminal.

The junction pointis a node between the bypass pathand the path. The junction pointis an end point of the bypass path. The junction pointmay coincide with the output terminal.

The switchis an example of a first switch and is arranged in series on the bypass path. The switchswitches between conduction and non-conduction of the bypass path. The “conduction of a path” means that the radio-frequency signal is capable of passing through the path. The “non-conduction of a path” means that the radio-frequency signal is not capable of passing through the path.

The switchis an example of the first switch and is arranged in series on the bypass path. The switchswitches between conduction and non-conduction of the bypass path.

The switchis arranged in series on the path. Specifically, the switchis connected between the branch pointand the power distributor. The switchswitches between conduction and non-conduction of the path.

The switchis arranged in series on the path. Specifically, the switchis connected between the lineof the power distributorand the junction point. The switchswitches between conduction and non-conduction of the path

The switchis arranged in series on the path. Specifically, the switchis connected between the lineof the power distributorand the junction point. The switchswitches between conduction and non-conduction of the path

Each of the switchestois capable of switching between a conduction state (on) and a non-conduction state (off). The state of each switch is switched depending on the operation mode of the amplifier circuit. This will be described in detail below.

The capacitoris arranged in series on the path. Specifically, the capacitoris connected to an output of the power distributorand the branch point. The capacitoris a DC-cutting capacitor that is provided to block direct-current components of the amplified radio-frequency signal.

The bias control circuitis a circuit to select a transistor used for amplification from multiple transistors included in the amplifier. In other words, the bias control circuitselects one or more transistors that are to be operated as amplifier transistors from the multiple transistors. A specific operation of the bias control circuitwill be described below along with the configuration of the amplifier.

The amplifier circuitdoes not necessarily include the capacitor. Alternatively, instead of the capacitor, DC-cutting capacitors may be respectively provided on the bypass path, on the bypass path, and between the branch pointand the power distributor.

Each of the paths,, andand the bypass pathsandis a signal line composed of a wiring, a via, an electrode, a terminal, and/or the like, which is formed of a conductive member made of metal or the like. The input terminaland the output terminalsandare terminals, electrodes, or the likes, which are positioned in end portions of the signal lines.

Each of the switchestois realized by a switching element, such as a field effect transistor (FET) or a bipolar transistor. The capacitormay be an individual passive component, such as a chip capacitor, or may be composed of a conductive pattern provided on a substrate.

2. Configuration of Amplifier

Next, the configuration of the amplifierwill be described with reference to.

As illustrated in, the amplifierincludes transistorsand. The amplifierfurther includes resistorsand, capacitorsand, and an inductor.

The transistorsandare FETs and function as the amplifier transistors of the common drain. In other words, each of the transistorsandamplifies the radio-frequency signal input into its gate and outputs the amplified radio-frequency signal. Although the FET is, for example, an n-channel metal-oxide-semiconductor field-effect transistor (MOSFET), the FET may be a p-channel MOSFET.

The gate of the transistoris connected to the gate of the transistor, the drain of the transistoris connected to the drain of the transistor, and the source of the transistoris connected to the source of the transistor. Specifically, the gate of the transistoris connected to the input terminalvia the capacitor. The gate of the transistoris connected to the input terminalvia the capacitor. In other words, the gates of the respective transistorsandare connected to each other via the capacitorsand. Each of the capacitorsandis a DC-cutting capacitor that is provided to block direct-current components of the radio-frequency signal input into the input terminal.

The drain of the transistoris connected to the drain of the transistorand power supply voltage VDD is supplied to the drain of the transistorand the drain of the transistor. The source of the transistoris connected to the source of the transistorto be connected to one end of the inductor. The inductoris provided to adjust the output impedance Z of the amplifier. The node between the sources of the transistorsandcorresponds to an output terminal of the amplifier.

Bias voltage is supplied from the bias control circuitto the gate of each of the transistorsandvia the resistoror. Bias voltage Biasto be supplied to the gate of the transistormay be equal to or may be different from bias voltage Biasto be supplied to the gate of the transistor. In the present embodiment, at least one of the bias voltages Biasand Biasis variable.